Purchasing door blanks for your home gives you a wider range of design opportunities than buying pre-hung doors. You'll often find more slab doors in stock, and you might even be able to pick up a vintage door to re-use for your home. Yet when the door comes without hinges, should you flush-mount the hinges? Or where do they go exactly?
The process of installing door hinges on door blanks and sinking them flush is a process called mortising. This allows the door to open and close properly.
Basics of Installing Door Hinges on Blanks
A door hinge is installed so that one half of the hinge is on the door frame and the other half of the hinge is on the side of the door. Unless the door is pre-hung on an attached doorframe, this is an essential step to hanging a door.
A door hinge should be mortised—or recessed—into the door so that the top surface of the hinge is flush with the door. Mortising gives a tighter fit and more strength to the door and hinge, but if the door frame is large enough, the door will still be able to open and close, as hinges will operate regardless of whether they are recessed or mortised or not. Still, many experts recommend mortising hinges.
When mortising, keep in mind that the hinge must be level across the surface. If it is uneven or if it is mounted below the surface level, the door will not close properly.
Mortising a door hinge with a hammer and chisel is the traditional method and it is still widely used today. Though it is a simple process, you do need to be slow and patient to avoid cutting too deeply and splintering away other parts of the door. If you do not own a quality wood chisel, buy one at your local home center or hardware store.
Types of Door Hinges
Understanding the types of door hinges will help you choose the right ones for your project.
- Ball-Bearing Door Hinges: These hinges have sealed pins that cannot be removed. These hinges swing easily, last for years, and are good for heavy doors.
- Pin Door Hinges: These classic hinges have pins that can be removed by tapping them upward with a nail and hammer. Pin door hinges are good for interior doors and are especially beneficial when you are undertaking a home project that requires door removal.
- Spring Door Hinges: With internal springs, these door hinges close a door automatically. Spring door hinges are good for garages and back doors.
Codes, Regulations, and Permits
Hinge placement affects the direction of the door swing. In some instances, the door must swing in the direction of egress. Check with your building department for door swing requirements.
Always wear eye protection when working with a hammer, chisel, and file. Chisels are sharp, so cut away from the direction of your body.
Equipment / Tools
- Wood chisel
- Metal file
- Cordless drill
- Tape measure
- Utility knife
- Old towel
- Door blank or slab
Determine the General Placement of the Hinges
If the door will swing inward, into the room, then the pin side of the hinge will be on the inside of the door. Place the top hinge 5 inches from the top of the door and the bottom hinge 10 inches from the bottom of the door. If the door frame is already mortised, follow that placement pattern for the door.
Mark the Hinge Placement on the Door
Spread the old towel on the floor to cushion the door. Place the door on its side, with the handle side of the door facing the floor. Use the tape measure to mark the on-center placement points for the hinges. Lay a hinge down on the mark. The pin side should be on the side of the door swing. The hinge must step back from the edge of the door. To achieve this, let the hinge drape open so that one side of the hinge hangs down, with the other end of the hinge resting on the side of the door. Mark around the hinge with a pencil.
If you find it difficult to see or follow the pencil marks, instead place a single screw in the hinge to hold it in place, and then use the utility knife to score along the edges of the hinge for a more distinctive line. Remove the screw and hinge once finished.
For holding the door on its side, it helps to have an assistant hold the door. You can also clamp it in place with a wood clamp securing the door to a solid object, such as a chair.
Cut the Outline With the Knife
With a fresh blade in place, use the utility knife to cut around the pencil marks to the depth of the hinge thickness (about 1/16-inch).
If you used the utility knife to mark the outlines of your hinge, use a small router set to the depth of the hinge to cut along the knife lines.
Sharpen the Chisel
Unless you have a new chisel, you will need to sharpen it. Lay the chisel on a solid flat work surface. File the chisel to sharpen it.
Mortise the Hinge
With the hammer and chisel, cut away the inside area of the pencil marks or knife cuts. Work slowly and be patient. Make sure that the depth does not exceed the thickness of the hinge. Flatten out the mortise area by gently scraping by hand with the chisel.
Check the Hinge Depth
Place the hinge in the mortise. Run your finger across the top of the hinge to verify that it is flush with the door surface. If the hinge is too high, work the mortise again with the chisel to remove more waste material.
If you accidentally cut the mortise area too deep, cut out a spacer with thin cardboard to raise the top of the hinge to the door level.
Install the Hinges
Use the cordless drill and the screws provided with the hinges to mount the hinges to the door.
When to Call a Professional
Because mortising door hinges can be an exacting process, call a fine carpenter to help you if you doubt your abilities. Mortising hinges does not allow for second chances if you make a mistake. If you need to mortise a large number of doors, you may want to have a carpenter do the time-consuming work for you.